McPhee's Karen starts singing '20th Century Fox Mambo' in a rehearsal before she transforms into the late iconic star in order to prove that she deserves the lead role in an upcoming Broadway play.

Auditioning for the lead role in a Marilyn Monroe musical, Katharine McPhee's Karen will be seen as the late iconic star when "Smash" returns with a new episode next week. A newly released sneak peek has teased what she will do in order to prove that she deserves the part.

The clip opens with Karen singing an original song "The 20th Century Fox Mambo" in what seems to be a rehearsal. Halfway through the performance, Karen transforms into Marilyn as the dancers around her also have their costumes changed.

Titled "The Callback", the upcoming episode will see Ivy (Megan Hilty) and Karen jumping through hoops for the brilliant but temperamental director Derek Wills (Jack Davenport) as they pursue the role of a lifetime. Meanwhile, Julia (Debra Messing) and her husband Frank (Brian d'Arcy James) are frustrated by the red tape of an international adoption process, and Eileen (Anjelica Huston) fights to finance her new musical in the midst of an acrimonious divorce.